Provided is a fermented milk-containing beverage for which long-term storage stability is extremely difficult, the beverage containing milk protein particles which have undergone modification in a fermentation process, wherein long-term coagulation and precipitation of the milk protein and syneresis are inhibited, perception of pastiness in terms of flavor is not present, ease of swallowing is good. This fermented milk-containing beverage contains fermented milk containing nonfat milk solids, soybean polysaccharides, and HM pectin. The nonfat milk solids content is 0.5 to 6.0 mass% with respect to the entire amount of beverage, the total content of the soybean polysaccharides and HM pectin is 0.3 to 0.8 mass% with respect to the entire amount of beverage, and the content ratio of the soybean polysaccharides and HM pectin is 3:1 to 1:4 in terms of mass ratio.針對含有在發酵過程受到變性的乳蛋白質粒子，且長期保存安定化極度困難的含發酵乳之飲料，提供抑制長期間乳蛋白質的凝集與沉澱，以及離水現象，進而其風味無黏糊感且順口的含發酵乳之飲料。該含發酵乳之飲料含有含非脂肪乳固形物之發酵乳、大豆多醣類與高甲氧基果膠；非脂肪乳固形物的含量對飲料全量為0.5~6.0質量%、大豆多醣類與高甲氧基果膠合計含量對飲料全量0.3~0.8質量%、大豆多醣類與高甲氧基果膠含量的比例以質量比計為3：1~1：4。
